Plant compound 'much more effective' than traditional anti-HIV drug

Justicia gendarussa, also known as the "willow-leaved Justicia," has significantly stronger antiretroviral properties than the common anti-HIV drug, AZT.

Azidothymidine, the first drug that was approved in the fight against AIDS in the 1980s, is still a main component in the medication mix commonly prescribed to HIV patients today. But new research may have found a plant-derived chemical compound that is much more effective than azidothymidine.

In the United States, the Centers for Disease Control and Prevention (CDC) estimate that around 1.1 million people have HIV, and 1 in 7 of them are not aware that they have it.

Due to awareness campaigns and efforts to prevent HIV, the number of new infections dropped by 19 percent between 2005 and 2014. The number of HIV-related deaths has also been falling since the mid-1990s, largely due to advances in HIV treatment.

Although there is yet no cure for HIV, antiretroviral therapy significantly slows down the progression of the virus. The first drug to have been approved in the fight against AIDS is azidothymidine (AZT).

Since 1987, however - the year in which AZT was approved by the U.S. Food and Drug Administration (FDA) - the virus has adapted to the drug. Today, HIV patients are given a combination of various drugs, of which AZT is often still the main component.

AZT works by inhibiting an enzyme that the HIV virus needs to replicate inside a host cell. This enzyme is called reverse transcriptase.

New research, published in the Journal of Natural Products, has found a plant compound that may be more effective at inhibiting this enzyme than AZT.

The chemical compound is called "patentiflorin A" and is derived from a medicinal plant found in East Asia: Justicia gendarussa.

The discovery is the result of a research effort extending over several years, carried out by an international team of scientists from the University of Illinois at Chicago (UIC), the Hong Kong Baptist University in Kowloon Tong, and the Vietnam Academy of Science and Technology in Hanoi.

The team was led by Lijun Rong, a professor of microbiology and immunology at the UIC College of Medicine, who has special expertise in identifying antiviral agents.

Patentiflorin A inhibits HIV 'much more effectively' than AZT

Prof. Rong and colleagues selected Justicia from a pool of more than 4,500 plants.

After separating the extracts of the stems and roots of this plant using bioassay-guided isolation - which is the most common procedure for separating extracted compounds based on their biological activity - the researchers found the "anti-HIV arylnaphthalene lignan glycoside" that is patentiflorin A.

Then, Prof. Rong and team assessed the effect of the compound against the M-tropic and T-tropic HIV isolates. "Tropism" refers to the type of cells that the virus is able to invade. M-tropism refers to the virus' ability to invade macrophages, while T-tropism refers to its ability to invade T cells, which are both white blood cells with key roles in immunity.

The tropism tests showed that patentiflorin A had "a significantly higher inhibition effect than the clinically used anti-HIV drug AZT."

"Patentiflorin A was able to inhibit the action of reverse transcriptase much more effectively than AZT, and was able to do this both in the earliest stages of HIV infection when the virus enters macrophage cells, and alter infection when it is present in T cells of the immune system," Prof. Rong explains.

He also notes that his team managed to synthesize the compound de novo, or "from scratch." He says:

"If we can make the drug in the lab, we don't need to establish farms to grow and harvest the plant, which requires significant financial investment, not to mention it has an environmental impact."

Prof. Lijun Rong

He concludes, "Patentiflorin A represents a novel anti-HIV agent that can be added to the current anti-HIV drug cocktail regimens to increase suppression of the virus and prevention of AIDS."

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